This generally relates to email transport rules and, in particular, email transport rule schemas which apply to instances of bifurcated emails having multiple recipients based on the recipients.
For email transport systems, bifurcation based on recipient is common. Frequently, one or more specific actions should be applied for a particular recipient or a particular group of recipients. For example, recipient specific actions may include stripping attachments of a message which includes particular recipients and signing/encrypting messages of certain recipients.
An example of such a system would execute the following rules:
{  For rule 1,   check condition,   execute actions if the condition is evaluated to true  For rule 2,   check condition,   execute actions if the condition is evaluated to true  For rule 3, ...}
The above rules result in actions that will apply to the entire message and affect all recipients. Thus, without recipient conditions, email administrators are unable to specify rules applying only to specific recipients. Such situations could restrict or make difficult what an administrator could do on a recipient by recipient basis. For example, in certain systems administrators could not specify a rule which would strip attachments only of a group of recipients (e.g., acmeGroup), such as:
IF a message recipient IsMemberOf “acmeGroup”Then Strip attachments “*.jpg”
The above rule does not allow an administrator to strip only attachments of an email to the group if the email includes addressees in addition to the group. This is because this rule would strip attachments on the entire message, instead of stripping attachments only for the message instance sent to the recipients belonged to the “acmeGroup”.